Arrangement in a mine which is capable of being neutralized

ABSTRACT

An arrangement in a mine which is capable of being neutralized, comprising detecting means (33) operative to detect a neutralization of the mine, and initiator means (3) adapted to initiate detonation of a spotter charge (5) incorporated in the mine in response to the detection of a neutralization, and a spotter (1) which is arranged to be propelled from the mine by said detonator charge to the surface of the ground, in order to disclose the location of the mine. A penetrator (4), which is intended to drive a pathway through the ground to facilitate passage of the spotter (1), is arranged forwardly of the spotter in the mine, as seen in its direction of travel. The spotter (1) is capable of forwardly driving the penetrator (4) during a first phase of the spotter firing sequence; and the arrangement further includes a separating device (9) which is intended to separate the spotter from the penetrator during a second phase of the firing sequence.

TECHNICAL FIELD

The present invention relates to an arrangement in a mine which iscapable of being disarmed or "neutralized" and which can be buried inthe ground and which incorporate detecting means effective to detect aneutralized mine, and an initiating device which in response to thedetection of a neutralization initiates the detonation of a markerfiring charge or "spotter" charge arranged in the mine and capable ofpropelling a spotter device in the mine to the surface of the ground inwhich the mine is buried, therewith to indicate the location of theneutralized mine.

BACKGROUND PRIOR ART

Such an arrangement is known to the art from, for example, SwedishPatent Specification SE No. 7905478-9. This earlier Patent Specificationdescribes and illustrates an anti-tank mine which incorporates aninitiator for initiating detonation of the mine, and a timing circuitwhich subsequent to a given time delay from the time of arming the mine,for example a time delay of 30-40 days, neutralizes the mine, if themine has not been detonated prior thereto. The mine incorporates aspotter charge which is detonated in response to the act of neutralizingthe mine and fires a spotter to the surface of the ground in which themine is buried, therewith to indicate the location of the neutralizedmine, the spotter being connected to the mine by means of a connectingline. The mine can then be dug from the ground and reactivated.

It is difficult, however, to dimension satisfactorily the force at whichthe spotter is propelled. For example, if this force is dimensioned soas also to resist hard earth layers, so that the spotter is reliablydriven to the surface of the ground, the speed at which the spottermoves may be excessively high in the case of lightly of loosely packedearth layers, such as to cause the connecting line to break and thespotter to disappear, thereby making it difficult to locate the mine.If, on the other hand the mine is dimensioned for a lighter drivingforce, the speed at which the spotter is propelled through the groundmay be too low, for example in the case of hard earth layers, for thespotter to penetrate to ground level.

DISCLOSURE OF THE INVENTION

Consequently, the object of the invention is to provide an arrangementof the aforesaid kind which will ensure that when fired the spotter willalways reach the surface of the ground in which the mine is buried,without being propelled at a speed which might cause the spotter todisappear from the site at which the mine is buried.

This object is achieved with the aid of an arrangement according to theinvention having the characterizing features set forth in the preambleto claim 1.

Further developments of the invention are set forth in the dependingclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to apreferred embodiment thereof illustrated in the accompanying drawings.

FIG. 1 is a longitudinal sectional view of the arrangement according tothe invention.

FIG. 2 is a cross-sectional view taken on the line II--II in FIG. 1,illustrating a screw-base forming part of the arrangement.

FIG. 3 illustrates the attachment of a spring forming part of thearrangement.

FIG. 4 illustrates the spotter during a firing sequence.

FIG. 5 is a block schematic illustrating the mine components intendedfor generating an initiating pulse for detonation of the spotter charge.

DESCRIPTION OF A PREFERRED EMBODIMENT

The arrangement according to the invention includes in general a spotterwhich in the illustrated embodiment comprises a spotter sleeve 1, whichin FIG. 1 is shown in an inactive position in a mine buried in theground 2 (in FIG. 1 the cover plate of the mine is illustratedschematically at 3), and which in FIG. 4 is shown during a firingsequence, accompanied by a penetrator 4. The arrangement furtherincludes a spotter charge 5 which fires the spotter sleeve 1 from themine, in response to a neutralization of the mine. When fired, thespotter sleeve 1 travels through an outer sleeve 6 rigidly connected tothe mine and, in the manner of a sabot, drives the forwardly locatedpenetrator 4 out of the outer sleeve 6, through the ground 2 and up intothe air.

The components forming part of the arrangement according to theinvention are described in detail hereinafter.

The outer sleeve 6 is rigidly connected to the mine by means of somesuitable fastener device, for example a screw or bolt joint, andcomprises a cylindrical sleeve which is open at both ends and which issuitably made of high-tensile steel. The sleeve is mounted vertically inthe mine, with the upper end of the sleeve opening through an aperture3a in the cover plate 3 of the mine. The sleeve edge defining the upperopen-end thereof is folded inwardly to form a folded edge 6a, whichabuts the forward end of the penetrator 4.

The penetrator 4 comprises a cylindrical sleeve, made suitably ofstainless steel, which is arranged co-axially with and within the outersleeve 6 and which can be displaced axially in relation thereto. One endof the penetrator 4 (the lower end in the FIGS.) is open, while theother end thereof is closed by means of an end wall 4a having a conicalinner edge. This has located centrally thereof an external grip 4b,which facilitates dismantling of the arrangement. Placed on theperipheral surface of the end wall 4a is an O-ring 4c, which is able toslide sealingly against the inner wall surfaces of the outer sleeve 6 asthe spotter sleeve and the penetrator pass along the sleeve during amarker firing sequence. Provided in the wall 4a are threethrough-passing apertures 4d, the function of which will be describedhereinafter.

The spotter sleeve 1, which may be made from a plastics material, iscylindrical in shape and is arranged within the penetrator 4 and axiallydisplaceable relative thereto. The spotter sleeve 1 is open at one end(the bottom end), whereas the other end of the sleeve is closed by meansof an end wall 1a having a forwardly facing conical edge which, during afiring sequence, lies against the conical inner edge of the wall 4a.

The spotter charge 5, for example pistol powder or some other suitablepowder charge, is accomodated in a container 7 which extends into thespotter sleeve 1 and which is attached, e.g. with the aid of asnap-fastener, to a screw-base 8 (illustrated separately in FIG. 2)screwed firmly into the bottom end of the outer sleeve 6. A draw springin the form of a coil spring 9 is connected at the upper end thereof tothe end wall 1a of the spotter sleeve 1, and at the bottom end thereofto the screw-base 8.

Mounted in an upper end surface of the screw-base 8, which may be madeof aluminium for example, is a fuse head 10 having connected thereto twoelectrical conductors 11 and 12, which pass through the screw-base 8 tothe other end surface thereof, where they are soldered firmly to apattern card 13 made of epoxy glass fibre. The conductors 11 and 12 arecovered with an electrical insulation, and each conductor passes througha respective lead-through in the screw-base 8.

At the location where the conductors are soldered to the pattern card 13there is provided in the screw-base a larger cavity 14 through whichboth conductors are drawn. The lead-through is suitably sealed with theaid of a silicone rubber seal, and to this end the cavity 14 is providedwith a rough surface, so that the silicone rubber obtains a firmer gripand therewith provides a better seal. The electrical insulation providedon the conductors may be given a length which ensures that the ends ofthe insulations are also covered by the silicone rubber, therebyeffecting a seal between the insulation and its associated conductor.Two contact sleeves 15 and 16 are soldered firmly to the pattern card 13and connected to the two electrical conductors 11 and 13 soldered to thefuse head 10, by means of a conductor pattern on the pattern card 13.The pattern card 13 is secured to the screw-base 8 by means of a screw17 and a tightening pin 18.

The coil spring 9 is varnished and is suitably made of a steel-gradehaving a low elastic limit. One end of the spring (the upper end in theFigures) is bent to form an eye, through which a screw 19 is passed andscrewed into the end wall 1a of the spotter sleeve 1, therewith tofasten the spring at said one end. The screw 19 passes through a bush 20mounted in a bore 21 passing through the end wall 1a. Formed in theforward part of the bore 21 is a hexagonal recess which accommodates anut 22, into which the screw 19 is screwed. Located between the eye insaid one end of the spring and the head of the screw 19 is a washer 23which is given a radius such as to reduce the risk of the springbreaking when stretched.

The other end of the spring 9 terminates in a straight portion 9a havinga length of about 9 mm and extending parallel with the centre axis ofthe spotter sleeve 1. This straight end portion 9a of the spring isanchored in a hole 24 in the screw-base 8 by means of a locking device25 illustrated in FIG. 3. This device incorporates a bore 26 whichcrosses the hole 24 and which has arranged therein a ball 27, which canbe forced against the spring portion 9a with the aid of a screw 28 in amanner to deform said spring portion and therewith secure it againstwith-drawal through the hole 24.

The fuse head 10 of the spotter charge is detonated in the mannerillustrated schematically in FIG. 5.

An electronic timing circuit 29 is arranged to send an electric pulse(indicated by the arrow A) to an initiator in the form of a detonationpulse generator 30 after a pre-set length of time has lapsed, forexample 40 days, provided that the mine has not been exploded prior tothe expiration of this time period. The generator 30 therewith deliversan electric pulse (indicated by the arrow B) to a force generator 31(e.g. a motor) which causes (indicated by the arrow C) a detonator rotor32 to turn from an armed position to a disarmed position. When the rotor32 is located in its disarmed position, an activator in the form of aswitch 33 is activated and closes an electric circuit from thedetonating pulse generator 30 to the fuse head 10 of the spotter charge.

The fuse head 10 therewith ignites the powder charge 5, generating apressure build-up which urges the spotter sleeve and the spring 9against the inner wall of the penetrator 4, the gas pressure causing thepenetrator to fracture the folded edge 5a of the outer sleeve 6 and tobe shot from the mine, and also through any camouflaging material thatmay have been placed over the mine. This firing sequence is illustratedin FIG. 4. During a first stage of the firing sequence, movement of thepenetrator 4 is accompanied by the spotter sleeve, and since the spring9 is attached to the spotter sleeve 1 and also to the screw-base 8,which is anchored to the mine via the outer sleeve 6, the spring willbegin to extend and stretch, when the penetrator, and therewith also thespotter sleeve, has reached a point at which the gas pressure isrelieved, i.e. during a second firing phase, the spring 9 attempts towithdraw the spotter sleeve from the penetrator 4. The spring 9therewith also functions as a separating means for separating the sleeve1 from the penetrator 4.

Gas under high pressure also flows through the afore-mentioned threeapertures 4d in the end wall 4 and into a space 34 located between theend walls 1a and 4a (c.f. FIG. 4), thereby to prevent the creation of apartial vacuum in the penetrator as the spotter sleeve is withdrawntherefrom. It will be understood that if the creation of a partialvacuum were to be permitted, the suction force generated thereby wouldprevent smooth separation of the penetrator from the spotter sleeve andcuase the spring to be torn off. The the pressurized gas flows throughthe apertures 4d there can be obtained a pressure of mutually equalmagnitude on both sides of the end wall 4a. When the pressure externallyof the penetrator subsequently falls rapidly away, the enclosed pressurewill assist in ejecting the spotter sleeve from the penetrator.

Upon leaving the ground, the penetrator 4 flies into the air at highspeed, while the spotter sleeve 1 and the withdrawn spring 9, the bottomend of which is constantly held anchored to the screw-base 8, fall ontothe ground in the close vicinity of the buried mine. The spring remainsin its extended shape due to the low elastic limit of the material fromwhich it is made (when a material passes its elastic limit, it is nolonger elastic and will not therefore return to its original shape anddimensions).

We claim:
 1. An arrangement in a mine which is capable of beingneutralized and which is intended for burial in the ground, includingdetecting means (33) operative to detect a neutralization of the mine,initiator means (30) adapted to initiate detonation of a spotter charge(5) incorporated in the mine in response to the detection of aneutralization, and a spotter (1) which is arranged to be driven by thedetonated charge from the mine to the surface of the overlying ground,in order to disclose the location of the mine, characterized in that apenetrator (4), which is intended to drive a pathway through the groundto facilitate passage of the spotter (1), is arranged forwardly of thespotter as seen in its direction of travel, said spotter being capableof driving the penetrator in said direction during a first phase of thespotter firing sequence; and in that the arrangement further includes aseparating device (9) which is intended to separate the spotter from thepenetrator during a second phase of the firing sequence.
 2. Anarrangement according to claim 1, characterized in that the separatingmeans comprises a spring (9) which is connected at one end to thespotter (1) and at the other end to the mine (8).
 3. An arrangementaccording to claim 1, characterized by means for providing the gasesgenerated by the spotter charge (5) access to an area (34) locatedbetween the penetrator (4) and the spotter (1), such as to cause agas-pressure build-up in said area, said gas-pressure being effective toassist in the separation of the spotter from the penetrator.
 4. Anarrangement according to claim 1, characterized in that the penetrator(4) and the spotter (1) are arranged to be ejected together from acylindrical sleeve (6) arranged in the mine.